PVC pipe spacing in trench

I am installing a large irrigation system. All pipes are PVC. The trench is about 8" wide and 12" deep. I have a 1 1/2" main irrigation line and a 1" PVC conduit for sprinkler wires running together. In some places, there are also one or two 1" PVC pipes carrying water after valves. So, in the worst case, there can be 4 PVC pipes in the same trench: (1) 1 1/2" PVC and (3) 1" PVC.

My question is how to best place these 4 pipes in the same trench. If I knew I would never dig it up and fix anything again, I would not care. But, chances are there will be a need for future digging/fixing/or just tapping into one of those pipes. When that happens, it will a nightmare to cut a pipe if the others are too close it.

Can I use PVC spacer? Does anyone has experience spacing PVC pipes? Any recommendations?

PVC pipe spacing in trench

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PVC pipe spacing in trench

Where are you located? 1 1/2 is pretty big for supply lines. Is your water main that big? I would use Polyethelene pipe instead of PVC. It goes in faster and you don't have to mess with glue, just crimp clamps. You can rent a machine that will slice your lawn and pull the poly pipe at the same time. It leaves little evidence you did anything. The only digging you'll need to do is for the heads.

Best way is to bring the supply into a valve box and supply a manifold consisting of the zone valves. Do you have a drawing of what you have planned?

PVC pipe spacing in trench

I am located in San Francisco Bay Area. We usually don't have freeze here. Lowest temperature I have seen was 36 F.

I already have the PVC pipes, so other pipe options is not an option for me. The irrigation system will be used for fruit orchard drip system as well as lawns. The total irrigation area is about 1 acre. Supply line is 2" sch 80 PVC. The 1.5" irrigation main line will be pretty long: about 1200 ft.

There will be 16 drip irrigation zones and 6 sprinkler zones. There will be 8 valve boxes distributed in this area. Almost every tree gets its own drip riser through a PVC pipe. It is like an underground grid of PVC pipes. I wanted to use the irrigation main trench to save on trenching if possible.

Getting back to main question: What do you think about PVC pipe spacing in a trench?

PVC pipe spacing in trench

I can't picture what you would have in one trench together. The PVC fittings will provide some spacing. Give yourself at least 2 inches between pipes. PVC is easy to work with and it cuts easily. If you ever had to repair a pipe, they have slip couplings that you can use for repair.